So Fix it

While modern air-conditioning systems use R-134 and other environmentally friendly rigerants, owners of vehicles manufactured before 1994 may have systems that use R-12 rigerant. Though the two rigerants are not compatible with one another, mechanics can adapt an older system for the new rigerant.

Differences

According to the automotive website Pro Car Care, R-12 rigerant is a chlorofluorocarbon (CFC) that erodes naturally occurring ozone. The substance consists of slightly larger molecules than R-134, and this difference makes a direct replacement of R-12 with the newer R-134 impractical. The automotive website AA 1 Car also points out that no one should mix R-12 with any other rigerant, as doing so can result in serious environmental damage while also presenting a significant safety hazard.

Retrofitting

Vehicle owners cannot directly replace R-12 with R-134 rigerant. However, mechanics can perform a retrofit that replaces air-conditioning components with new lubricants and seals designed to contain R-134.

Warning

While often considered a more environmentally friendly rigerant, R-134 is a greenhouse gas and can still cause environmental problems if allowed to vent directly into the atmosphere, according to the automotive website Garage-Pak. In addition, Pro Car Care notes that either rigerant will instantly freeze skin and other surfaces if allowed to vent.